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Thread: Blower motor 3/4 speed tripped/reset c/b... but c/b is 40a

  1. #1
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    Blower motor 3/4 speed tripped/reset c/b... but c/b is 40a

    While driving yesterday, my blower motor 3/4 speeds cut out. 1/2 still worked, and 3/4 came back online a few minutes later. I know this means the c/b tripped, and then reset, so I checked it today expecting to see some corrosion, or too low of a c/b (25a instead of 30a).

    I pulled the cover today and it’s a 40a c/b. I had replaced the original c/b last year with one from DMCCA (I was unaware of the size at the time, just used the one Danny Botkin handed me).

    So what gives? 30a shouldn’t trip like that and 40a definitely shouldn’t. Is my blower motor on the way out/pulling too much current? It functions fine and makes no weird noises. I use it on speed 4 the vast majority of the time (Las Vegas).
    5 speed, grooved hood, grey interior (Nov '81)
    QA1 coilovers, Delorean.eu LCA brackets, DPNW Poly swaybar bushings, DMCMW shock tower bar, Deloreana.com convex mirrors, DPNW Toby Tabs, DPI exhaust, C4 Corvette third brake light, PJ Grady tail light boards, Bitsyncmaster relays

  2. #2
    Senior Member Gregadeth's Avatar
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    Make sure you're looking at the circuit breaker for the blower motor and not the cooling fans. They're right next to eachother and they could be installed in the wrong slot. The blower motor circuit breaker should have four wires, the cooling fans' has only two.

  3. #3
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    Quote Originally Posted by Gregadeth View Post
    Make sure you're looking at the circuit breaker for the blower motor and not the cooling fans. They're right next to eachother and they could be installed in the wrong slot. The blower motor circuit breaker should have four wires, the cooling fans' has only two.
    Yes, I am. It’s the only c/b I have. I've replaced the cooling fan c/b with Dave/bitsyncmaster’s fused relay.
    5 speed, grooved hood, grey interior (Nov '81)
    QA1 coilovers, Delorean.eu LCA brackets, DPNW Poly swaybar bushings, DMCMW shock tower bar, Deloreana.com convex mirrors, DPNW Toby Tabs, DPI exhaust, C4 Corvette third brake light, PJ Grady tail light boards, Bitsyncmaster relays

  4. #4
    Senior Member AugustneverEnds's Avatar
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    How does the spade connector on the blower motor itself look? I had a poor connection there and it would cut out on speed 4 but was fine otherwise. Also check the connection to the blower motor resistor.
    Nick A.

    1988 BMW 325is
    1982 DeLorean DMC-12
    1989 Jaguar XJ6

  5. #5
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    The cooling fans are supposed to have the 40 A C/B, not the cabin fan. If the C/B is popping it could be the fan motor is on it's "last legs" or the C/B is bad. Check the current draw.
    David Teitelbaum

  6. #6
    Senior Member Bitsyncmaster's Avatar
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    You would need to measure the fan current on speed 4 to determine if the fan or circuit breaker is bad. It may just be you have a bad breaker. To measure the current you would probably need a clamp on type of DC current meter since the normal current draw I think is around 25 amps on speed #4.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  7. #7
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    I pulled the resistor and it appears to be in good condition. IDK which pins should give how much resistance, so I didn’t measure it.
    The male end of the power connection on the motor though looks like it has overheated and melted the rubber surrounding it.

    974FCD3F-08FF-4D32-8FDD-5A4C3550DA49.jpg

    I’m off to Lowes to see if I can “rent” an amp meter.
    5 speed, grooved hood, grey interior (Nov '81)
    QA1 coilovers, Delorean.eu LCA brackets, DPNW Poly swaybar bushings, DMCMW shock tower bar, Deloreana.com convex mirrors, DPNW Toby Tabs, DPI exhaust, C4 Corvette third brake light, PJ Grady tail light boards, Bitsyncmaster relays

  8. #8
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by jackb View Post
    I’m off to Lowes to see if I can “rent” an amp meter.
    Most mutimeter amp limit is 10 amps. Many even fuse that range. Your going to pull much more than 10 amps.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  9. #9
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    Quote Originally Posted by Bitsyncmaster View Post
    Most mutimeter amp limit is 10 amps. Many even fuse that range. Your going to pull much more than 10 amps.
    Do you have any advice on how to isolate the problem to the motor?
    5 speed, grooved hood, grey interior (Nov '81)
    QA1 coilovers, Delorean.eu LCA brackets, DPNW Poly swaybar bushings, DMCMW shock tower bar, Deloreana.com convex mirrors, DPNW Toby Tabs, DPI exhaust, C4 Corvette third brake light, PJ Grady tail light boards, Bitsyncmaster relays

  10. #10
    Senior Member Bitsyncmaster's Avatar
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    Quote Originally Posted by jackb View Post
    Do you have any advice on how to isolate the problem to the motor?
    I don't have this meter but from the description it does look like it will read DC current and is not very expensive.

    https://www.amazon.com/Meterk-Multim...DHNBF5W380VKMZ
    Dave M vin 03572
    http://dm-eng.weebly.com/

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